hotfix: fix a problem with multiple UEs
The symptom: when two UEs do uplink traffic at the same time, the eNB fails to decode data sometimes. This has been seen with FDD and 50 RBs. This generates a cascade of other problems leading to disconnection/reconnection events seen in the log. The problem: there are probably many, but one obvious bug was found while analyzing some logs. Scheduling in the same TTI one UE's uplink traffic and random access (msg3) was done in the same RB. This commit fixes this simple case. It is probably not the end of the story. This is a hotfix, that does not change the code much. We need to use vrb_map_UL properly all over the places. Today is not used, but this is the way to go (most probably).